Breaks From Prostate Cancer Therapy Safe: Researchers

Stop-and-start hormone-deprivation therapy for localized prostate cancer doesn't shorten overall survival compared to continuous treatments, and yields fewer side effects such as impotence and hot flashes, a large new study suggests.

A team of Canadian, British, and American researchers found that intermittent hormone treatments — which suppress circulating male hormones such as testosterone that "feed" prostate tumors — don't increase the risk of disease progression. Intermittent treatment also doesn't increase the chances that patients whose prostate-specific antigen (PSA) levels are slowly rising will eventually die from prostate cancer.

"There has been a lot of work (in this area) over the last two decades, so we figured there would be an improvement in quality of life and hoping there was no detriment to survival," said study author Dr. Juanita Crook, professor of radiation oncology at the University of British Columbia. "That was the one thing that was unknown, but our impression is that people are not dying sooner on intermittent therapy than continuous."

For the study, published Sept. 6 in the New England Journal of Medicine, nearly 1,400 patients whose localized prostate cancer was treated with surgery and/or radiation were split into two groups. One set received continuous hormone-deprivation therapy — a mainstay treatment for prostate cancer that has spread — while the rest were treated in eight-month cycles punctuated by months-long "breaks" depending on their PSA levels.

Slowly rising PSA levels may indicate the progression of prostate cancer, even if no evidence of the disease shows up on other tests such as MRI and CT scans. Study participants on stop-and-start hormone-deprivation treatments were placed back on therapy if their PSA scores grew to 10 or higher, or they experienced clinical symptoms of disease progression, Crook said.

After a follow-up of nearly seven years, only 14.2 percent of all participants had died from prostate cancer, with an overall survival of 8.8 years in the intermittent-therapy group and 9.1 years in the continuous-therapy set.

Side effects associated with hormone-deprivation therapy, such as erectile dysfunction, hot flashes, bone loss, and depression, were less common among the intermittent treatment group, Crook said.

"There were many quality-of-life benefits to intermittent therapy, despite a similar overall survival," Crook said. "Even if they didn't regain erectile function ... they had less fatigue and improved urinary function, which were very important to them as well."

Those on intermittent therapy had one-third of the treatments of the continuous therapy group, she added. "So there's a very significant cost savings ... with improved quality of life and no overall loss of survival," she said. "It's a triple win."

Dr. Louis Potters, chairman of radiation medicine at North Shore-LIJ Health System in New Hyde Park, N.Y., said the study will help him structure conversations with some of his prostate cancer patients who face similar treatment choices.

"We need to now focus on (learning) the optimal timing of the initiation of this treatment," he said. "Because it's clear that patients aren't necessarily going to die in droves if they have a recurrence following primary treatment. The question is, When do they need to start this type of therapy?"

Crook noted that her study wasn't designed to answer that question, which could take many more years of research, but contended that the current evidence demonstrates that intermittent hormone therapy can become the standard of care for patients like those studied.

"Intermittent therapy can't be used just arbitrarily," she said. "(Clinicians) need to follow a template and a schedule, and this is the one we have experience with. People have to be very careful in their interpretation of the study and the application of results."

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